[Signin][Android] Extend mobile-identity-consistency flag

Bug: 1046254
Change-Id: I75b97c83d68bb2b04e3d5bfc1ee843601dbc0cdb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2023829
Auto-Submit: Boris Sazonov <bsazonov@chromium.org>
Reviewed-by: Tanmoy Mollik <triploblastic@chromium.org>
Commit-Queue: Tanmoy Mollik <triploblastic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735839}

chrome/browser/flag-metadata.json

@@ -2598,7 +2598,7 @@
   {
     "name": "mobile-identity-consistency",
     "owners": [ "bsazonov", "droger", "msarda" ],
-    "expiry_milestone": 80
+    "expiry_milestone": 84
   },
   {
     "name": "mouse-subframe-no-implicit-capture",